content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.observable.internal.operators;
  
  import static org.junit.Assert.assertEquals;
  import static org.mockito.ArgumentMatchers.any;
  import static org.mockito.Mockito.*;
  
  import java.util.Arrays;
  
  import org.junit.*;
  import org.mockito.InOrder;
  
  import io.reactivex.common.Schedulers;
  import io.reactivex.common.exceptions.TestException;
  import io.reactivex.observable.*;
  import io.reactivex.observable.observers.TestObserver;
  
  public class ObservableSkipLastTest {
  
      @Test
      public void testSkipLastEmpty() {
          Observable<String> o = Observable.<String> empty().skipLast(2);
  
          Observer<String> observer = TestHelper.mockObserver();
          o.subscribe(observer);
          verify(observer, never()).onNext(any(String.class));
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testSkipLast1() {
          Observable<String> o = Observable.fromIterable(Arrays.asList("one", "two", "three")).skipLast(2);
  
          Observer<String> observer = TestHelper.mockObserver();
          InOrder inOrder = inOrder(observer);
          o.subscribe(observer);
          inOrder.verify(observer, never()).onNext("two");
          inOrder.verify(observer, never()).onNext("three");
          verify(observer, times(1)).onNext("one");
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testSkipLast2() {
          Observable<String> o = Observable.fromIterable(Arrays.asList("one", "two")).skipLast(2);
  
          Observer<String> observer = TestHelper.mockObserver();
          o.subscribe(observer);
          verify(observer, never()).onNext(any(String.class));
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testSkipLastWithZeroCount() {
          Observable<String> w = Observable.just("one", "two");
          Observable<String> observable = w.skipLast(0);
  
          Observer<String> observer = TestHelper.mockObserver();
          observable.subscribe(observer);
          verify(observer, times(1)).onNext("one");
          verify(observer, times(1)).onNext("two");
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      @Ignore("Null values not allowed")
      public void testSkipLastWithNull() {
          Observable<String> o = Observable.fromIterable(Arrays.asList("one", null, "two")).skipLast(1);
  
          Observer<String> observer = TestHelper.mockObserver();
          o.subscribe(observer);
          verify(observer, times(1)).onNext("one");
          verify(observer, times(1)).onNext(null);
          verify(observer, never()).onNext("two");
          verify(observer, never()).onError(any(Throwable.class));
          verify(observer, times(1)).onComplete();
      }
  
      @Test
      public void testSkipLastWithBackpressure() {
          Observable<Integer> o = Observable.range(0, Observable.bufferSize() * 2).skipLast(Observable.bufferSize() + 10);
          TestObserver<Integer> ts = new TestObserver<Integer>();
          o.observeOn(Schedulers.computation()).subscribe(ts);
          ts.awaitTerminalEvent();
          ts.assertNoErrors();
          assertEquals((Observable.bufferSize()) - 10, ts.valueCount());
  
      }
  
      @Test(expected = IndexOutOfBoundsException.class)
      public void testSkipLastWithNegativeCount() {
          Observable.just("one").skipLast(-1);
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Observable.just(1).skipLast(1));
      }
  
      @Test
      public void error() {
          Observable.error(new TestException())
          .skipLast(1)
          .test()
          .assertFailure(TestException.class);
      }
  }
  